Planar, microstrip antennas have characteristics often sought for portable communication devices, including advantages in cost, efficiency, size, and weight. However, such antennas generally have a narrow bandwidth which limits applications. Several approaches have been proposed in the art in an effort to widen the bandwidth of such structures. One such approach is described in U.S. Pat. No. 5,572,222 issued to Mailandt et al. on Nov. 5, 1996, for a Microstrip Patch Antenna Array. Here, a microstrip patch antenna is constructed using an array of spaced-apart patch radiators which are fed by an electromagnetically coupled microstrip line. Generally, with such structures, electromagnetic coupling between radiators is negligible, as it is regarded as a second-order undesired effect. Mailandt's structure is contemplated for use in fixed communication devices. For portable communication devices, size and weight considerations are paramount and such structures may not be suitable. Many other prior art approaches have similar drawbacks.
Current trends demand a reduction in size, weight, and cost for portable communication devices. Planar patch antennas could provide a part of the solution if bandwidth concerns are addressed without a significant compromise in size and weight. Moreover, these antennas can provide additional advantages in terms of directivity and efficiency. Therefore, a new approach for planar patch antenna with increased bandwidth is needed.